Waterbeds are, as a general rule, characterized by water-filled bladders formed of flexible water impervious sheet material atop which persons using the beds lie to be buoyantly supported thereby. The bladders are most commonly supported atop platforms made of plywood or the like to position the top planes or surfaces of the bladders in predetermined, desired, space relationship above the surface of the deck or floor on which the beds are supported.
Some waterbeds are provided with one large bladder of rectangular planned configuration while others include a plurality of elongate tubular bladders arranged in side-by-side relationship to establish an assembly of bladders of desired rectilinear planned configuration.
The bladders of such beds are partially or slack-filled with water so that the upwardly disposed top or body engaging and supporting surfaces of the bladders will readily conform to the shape and contour of the bodies of the users and enable the users to be buoyantly supported by the water therein.
Due to the highly flexible or "fluid" nature of water-filled bladders for such beds, it is necessary that the platforms upon which the bladders are supported be provided with upwardly extending frames about their perimeters to support and retain the bladders against horizontal or outward displacement and to control and assure desired and proper functioning of the whole of the bed structures.
In many waterbeds, the retaining frames include side and end boards that are fixed to and project upwardly from the outer perimeters of the platforms to occur outward of and support the outer perimeters of the bladders and to prevent undesired outward displacement thereof. This kind of platform and retaining frame assembly is commonly referred to as a "hard-sided bed frame." In the case of waterbeds with hard-sided bed frames, the standard operating depth or vertical extent of the bladders is approximately 9" and the boards of the frames are made to project approximately 9" above their related platforms where they present hard edges about the upper outer perimeters of the bladders which are often extremely awkward, difficult and discomforting obstructions that the users of the beds must cope with when entering, using and departing from the beds. Further, as is well known in the art, the unitized platforms and side and end walls of hard-sided waterbed frames are large, heavy, and difficult or troublesome to store, transport and install.
In an effort to overcome and avoid the numerous shortcomings and undesirable characteristics of hard-sided waterbed frames, the prior art provides what are referred to as "soft-sided bed frames" that include flat horizontal platforms of plywood or the like with retaining frames of soft, flexible and resilient foam plastic that project up from the perimeters of the platform to occur about and support the outer perimeters of the bladders, in essentially the same way that hard-sided waterbed frames do. The soft plastic frames of soft-sided waterbed frames are such that they yield and compress under the weight of the users of the beds as the users enter and leave the beds and are sufficiently soft and yielding so that they cause little or no discomfort to the users, when the users' bodies come into contact therewith.
A serious shortcoming that characterizes some soft-sided bed frames is the fact that the foam sides and end walls of those frames must be of substantial thickness (from the inside to the outside surfaces thereof). That is, rather than being 11/2" to 2" thick, they must, for example, be 8" to 10" thick; thereby decreasing the inside longitudinal and lateral dimensions of the frame structures as much as 16" to 20" less than a hard-sided bed frame structure (assuming that the outside dimensions of the bed are let to remain standard).
Other soft-sided waterbed frame structures provided by the prior art overcome the above-noted shortcomings by tapering the inside surfaces of the side and end walls of the frames outwardly and upwardly so that the strength and capacity of the frames to effectively support the sides and ends of their related bladders diminish upwardly as the hydrostatic forces of the water (within the bladders) acting upon them diminishes. The above practice, together with using slightly smaller bladders, or by filling the bladders with slightly less water, enables the art to provide soft-sided bed frames having standard outside dimensions without adverse reduction of the dimensions of the top, flotation wall of the bladder.
Another serious shortcoming that is found to exist in soft-sided waterbed frames is the fact that the side and end walls of the frames must be fixed or secured to their related platforms at the time of manufacturer and establish unitary bed frame structures that are large and difficult to store, ship, install and the like.
Yet another serious shortcoming that is found to exist in soft-sided waterbed frames of the character referred to above resides in the fact that the foam plastic side and end walls, that are unitary parts cut from large blocks or slabs of foam plastic, must be contained and retained in soft flexible jackets or envelopes of sheet plastic or fabric that are utilized to fasten or secure those frame parts to their related platforms, to provide an attractive surface and to protect the foam plastic parts from wear, and the like. Unfortunately, as the above-noted structures are used and the foam plastic walls are repeated compressed and let to expand both vertically and horizontally, the foam plastic walls are slowly and progressively caused to stretch, warp and turn or twist within their envelopes and to become so displaced and distorted that the frames can no longer function as they should and become so unattractive that the frames must be disposed of and replaced with new frames. While the foregoing tendency for the foam plastic parts to distort and become displaced, as noted above, can be minimized by several different means and by exercising special care when producing the frames, the use of those means and that care that must be exercised is costly of time and/or materials and notably adds to the cost of the bed frame structures.
Some in the prior art provide soft-sided waterbed frame structures of the general character referred to above wherein the longitudinally extending lower side edges of the envelopes about the foam plastic walls are fastened to the platforms to enable the users of those frames, when making up their beds, to tuck the edges of their sheets and/or blankets between the bottoms of the walls and their related edge portions of the top surfaces of the platforms. This enables the users to make up their beds in a neat, attractive and most acceptable fashion. The principal shortcoming of the above-noted innovation in soft-sided waterbed frames resides in the fact that the outer perimeter portions of the platforms must be suitably dressed up with costly upholstery or the like. Further, due to the limited securement of the walls of such frames to their related platforms, the assemblies become almost impossible to store, transport and install, since the walls, in whole or in part, tend to pivot and swing about relative to the platforms whenever the assemblies are tipped and/or turned, as when being stored, transported and installed. The use of tape, straps, wrappings and the like to hold the parts in position prior to being put to use have proven to be so inefficient, costly and/or inconvenient, that many retailers and installers of waterbeds would prefer not to handle them.